US3203790A

US3203790A - Extruded flints and process for making same

Info

Publication number: US3203790A
Application number: US183023A
Authority: US
Inventors: Bungardt Walter
Original assignee: Ronson Corp
Current assignee: Ronson Corp
Priority date: 1955-11-22
Filing date: 1962-03-28
Publication date: 1965-08-31
Anticipated expiration: 1982-08-31
Also published as: DE1017507B; FR1161748A

Description

United States Patent 12 Claims. b1. 15-152 This is a continuation-in-part of application Serial No. I

623,798, filed November 23, 1956, now abandoned.

My invention generally relates to pyrophoric alloys and is more particularly directed to novel pyrophoric alloy compositions suitable for extrusion.

Considered from another aspect, my invention is concerned with an improved and simplified process for the extrusion of flints from pyrophoric alloy compositions and with the flints obtained thereby.

While flints for use in cigarette lighters and the like were originally produced by casting methods, such flints have, in recent years,'bee n manufactured by extrusion, as extrusion, of course, increases the plant output, simplifies the manufacture and may be carried out with considerably less expenditure than casting methods. Further, the general quality of extruded flints including the pyrophoric characteristics compare favorably with and are in many respects superior to that of cast flints. For these reasons, the industry has generally adapted extrusion processes for the production of flints.

Extruded as well as cast flints consist essentially of cerium (misch metal) iron alloys. However, those skilled in the art will readily realize that an alloy which may produce satisfactory flints by casting is not necessarily suitable as a raw material for extruded flints. This is so because the problems and considerations underlying the extrusion of flints are entirely different from those prevailing in casting methods. In fact for many decades it was believed that the extrusion of cerium (misch metal) iron alloys was not feasible and in this connection I refer to my US. Patent 2,660,301 wherein I disclosed for the first time a commercially practical extrusion process for flint material and explained the obstacles which have to be overcome.

However, although my basic invention as embodied in said US. patent has been considered and proved to be a revolutionary advance in this particular art, the extrusion of flints from cerium (misch metal) iron alloys is still plagued by some serious problems. The most serious ditficulty in the manufacture of flints or flint rods by extrusion from pyrophoric cerium (misch metal) iron alloys resides in the extremely high extrusion pressure which in present day processes is necessary for extruding the alloy composition through the extrusion die. Pyrophoric alloys used for the extrusion of flints ordinarily contain about 4.5 to 40% of iron in addition to the cerium (misch metal) and such alloy composition can only be extruded at pressures between 5,000 to 16,000 kg. per square centimeter and at extrusion temperatures between 400-500" C. The particular pressure required is a function of the iron content in the alloy and increases with increasing amounts of iron. It is obvious that such high pressures require elaborate and excessively expensive extrusion presses, which moreover are, of course, subjected to considerable wear and tear. As the extrusion tools have to be frequently replaced and/or repaired, the intended gain and advantage by using extrusion instead of casting methods is therefore considerably negated or offset by the expenditure in apparatus. In this connection, I wish to state that attempts have previously been made to reduce the extrusion pressure by alloying the basic alloy composi- 3,203,790 Patented Aug. 31, 1965 ice tion with additional metals. Thus in my own US. Patent 2,792,301 I have disclosed certain metals which under stated conditions facilitate the extrusion.

In the production of flints by casting as distinguished from extrusion it has been suggested to add appreciable amounts of copper or zinc to the alloy mixture to increase the resistance of the flints to distintegration. Thus, US. Patents 2,408,400 and 2,389,198, for example, which are concerned with the production of flints by casting, recommend that at least 1.2% of copper are added in addition to silver, nickel and chromium. I have carriedout extensive experiments'with this and other alloy compositions intended for casting with a view of ascertaining whether or not the teachings relating to the casting of flints could be beneficially made use of for the purpose of reducing the working pressure in the extrusion of flints.

' The results of my experiments are that these prior art casting compositions containing copper, zinc and other metals cannot in fact be extruded and therefore do not contribute anything of value to the extrusion art and particularly have no bearing on the reduction of the extrusion pressure. For the purpose of substantiating this contention, the following should be considered: The extrusion of pyrophoric alloy compositions is by necessity carried out at temperatures at which the billet or ingot to be extruded is in a plastic state. If the optimum extrusion temperature is abovethe melting point of one or several of the metals -of the alloy composition, this metal or metals liquify and the liquid phase seriously impairs the extrusion properuand in many cases renders extrusion impossible. Thus, for example, I have attempted to extrude the alloy compositions disclosed in US. Patent 2,408,400 and 2,389,198 previously referred to, but was not successful although I increased the extrusion pressure to 35 tons. The reason for my failure was that the composition formed a substantial amount of liquid phase which soiled and blocked the extrusion tools of the press.

It is, accordingly, a primary object of this invention to provide for an alloy composition which may be extruded at considerably lower pressures than was hitherto possible.

It is also an object of this invention to provide an extrusion process for the extrusion of flint material which [may be carried out at lower pressure values than heretofore.

Anoth r object of the invention is to provide extruded flints of excellent quality having superior pyrophoric characteristics.

Generally, it is an object of this invention to improve on the art of extruding flints as hitherto practiced.

Briefly, and in accordance with this invention, 1' have ascertained that the addition of small amounts of copper wit-bin predetermined limit ranges, to prior art extrusion alloy compositions considerably facilitates the extrusion procedure and permits the extrusion to be carried out at considerably lower pressure values than was hitherto feasible.

In my previous US. Patent 2,792,301, I have already suggested certain measures with a view to decreasing the required pressure for the extrusion procedure. Thus, in the prior patent referred to, I have proposed to admix the basic alloy composition with metals such as titanium, cadmium, magnesium, calcium, aluminum, barium, zirconium or beryllium in predetermined quantities, i.e., 0.3% to 10%, preferably 0.3% to 1%.

I have found that although the admixture of the elements referred to has in many-instances a most beneficial influence on the reduction of the extrusion pressure, the "addition of such metals within the stated ranges may somet1mes lead .to difliculties and is therefore undesired. This is so because some of the enumerated metals, erg. and zirconium, alloy with the basic cerium (misch metal)-iron composition only with difficulty, particularly if amounts in excess of 0.3% are employed. If the period for alloying the addition metals with the basic composition is protracted, the composition has to be maintained in molten condition for relatively long periods which, of course, results'in metal losses. Further, some of the addi tion metals may adversely effect the corrosion resistance, shelf life and/or the pyrophoricity of the extruded fiints.

-In accordance with my present invention, I have con clusively established that small copper additions to the basic cerium (misch metal)-iron alloy composition overcome the drawbacks referred to and yet significantly reduce the extrusion pressure, provided the copper is added within a range of 0.05-0.45%

The following Table I clearly establishes the beneficial effect on the working pressure of the addition of copper within the stated range.

*Not; extrudable because of partial liquefaction.

It will be noted that the extrusion pressure is 5100 kg./-cm. if the basic alloy composition is lacking copper, While copper additions to up to 0.45% result in a significant pressure reduction.

Further, it should be emphasized that the upper limit of 0.45% of copper is critical as larger amounts of copper in alloy compositions cause a partial liquification of the basic alloy composition. This is indicated in the table by test 47lb. In this connection I refer to my above remarks and also .to German Patent 891,824, Where this matter has been dealt within detail.

In analyzing the results of my tests as tabulated in Table I and considering the partial liquefaction of the alloy upon admixtures of copper in excess of 0.45%, I attempted to increase the copper content of the alloy while at the same time decreasing the extrusion temperature. As the partial liquefaction is, of course, dependent on the temperature, my reasoning was that a lowering of the working temperature would allow .me'to add larger amounts of copper without resulting liquefiaction. The results of my tests in this regard were, however, very discouraging. While I succeeded in extruding alloy compositions containing .up to 0.90% of copper at a temperature of 440 C., ie. a temperature which is 40 C. lower than that of Table I, the extrusion pressure again rose to a considerable extent. My tests in this respect are tabu- *Not extrudable because of partial liquefaction.

In comparing the results of Tables I and II it will be observed that, for example, a copper content of 0.90% requires an extrusion pressure of 4300 kg./cm. at 440 C., while the corresponding pressure is only 2100 kg./cm. at 480 C. if the copper content is 0.45%. Therefore, the upper copper limit of 0.45% is critical if the extrusion pressure is to be reduced. In this connection it will be realized that from a practical point of view the reduction of the pressure is more desirable and important than a reduction in the working temperature.

According to another embodiment of my invention, I have ascertained that a further addition of one or several of the metals titanium, magnesium, calcium, beryllium, barium, aluminum and zirconium is efiective further to reduce the extrusion pressure and to improve the quality of the extruded fiints, provided these metals are added in minute quantities not exceeding 0.3%. Thus, if, for example, the basic ceriurn (misch metal)-iron composition is alloyed with 0.05-0.45% of copper and 0.2% of titanium or zirconium, the extrusion pressure is still further reduced.

Tests in this respect are tabulated in Table III.

TABLE III Composition of alloy in percent by Extrusion weight pressure in kg./cm. Test No. at 480 C. Cerium Additional and after (misch Fe Cu elements 30 minutes metal) of preheating treatment 80. 2 19. 6 0.20% Mg 4, 800 80. 05 19. 5 0. 21 0.24% Mg" 3, 000 79. 19. 8 0.25% Al 4, 900 79. 92 19. 6 0. 25 0.23% Al- 2, 900

The invention will now be described in connection with a specific example, it being understood, however, that this example is given by way of illustration and not by way of limitation, and that many changes may be performed Without departing in any way from the scope and spirit of this invention as recited in the appended claims.

Example 1 This example illustrates test 471a of Table I above. An alloy composition comprising 80.25% by weight of cerium (misch metal) and 19.3% of iron was alloyed with 0.45 of copper and cast into-billet or ingot form. The alloy billet was thereafter heated to about 480 C. for 30 minutes and the billet was inserted into an extrusion press and was extruded into thin rods of 2 to 6 mm. diameter at an extrusion pressure of 2100 kg. per square centimeter. The extruded rods were thereafter cut down into individual flints of suitable length.

As control, the test was repeated with an alloy ingot which did not contain the copper addition. Extrusion only took place at a working pressure of at least 5100 kg. per square centimeter at the same temperature (see test 468a).

Similar tests were carried out to arrive at test results 469, 470, 471 and 4711;.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What I claim is:

1. A pyrophoric alloy composition suitable for extrusion essentially consisting of about 4.5 to 40% of iron and 0.05 to 0.45% of copper, the remainder being cerium (misch metal).

2. An extruded flint essentially consisting of about 4.5 to 40% of iron and about 0.05 to 0.45 of copper, the remainder being cerium (misch metal).

3. An extruded flint essentially consisting of about 18 to 22% of iron and about 0.05 to 0.45 of copper, the remainder being cerium (misch metal).

4. A pyrophoric alloy composition suitable for extrusion essentially consisting of about 4.5 to 40% of iron,

0.05 to 0.45% of copper, and a minute quantity of at least one metal selected from the group consisting of titanium, magnesium, calcium, beryllium, barium, aluminum and zirconium, said quantity being less than 0.3%, the remainder being cerium (misch metal).

5. An extruded flint essentially consisting of about 4.5 to 40% of iron, 0.05 to 0.45 of copper, and a minute quantity of at least one metal selected from the group consisting of titanium, magnesium, calcium, beryllium, barium, aluminum and zirconium, said quantity being less than 0.3%, the remainder being cerium (misch metal).

6. An extruded flint essentially consisting of about 18 to 22% of iron, 0.05 to 0.45 of copper and a minute quantity of at least one metal selected from the group consisting of titanium, magnesium, calcium, beryllium, barium, aluminum and zirconium, said quantity being less than 0.3%, the remainder being cerium (misch metal).

7. A process of producing flint rods by extrusion which comprises extruding a pyrophoric alloy in ingot form and essentially consisting of about 4.5 to 40% of iron and 0.05 to 0.45% of copper, the balance being cerium (misch metal) at a temperature of about 400 to 500 C. and at the lowest working pressure at which extrusion is possible.

8. The process as claimed in claim 7, wherein the alloy is preheated before being extruded.

9. The process as claimed in claim 7, wherein the extrusion pressure is about 2100 and 3500 kg./cm.

tionally contains a minute quantity of at least one metal selected from the group consisting of titanium, magnesium, calcium, beryllium, barium, aluminum and zirconium, said quantity being less than 0.3%, the remainder being cerium (misch metal).

11. In a process of extruding flints from alloy compositions in ingot form, wherein the alloy composition essentially consists of about 4.5 to of iron, the remainder being cerium (misch metal), and the alloy composition is extruded at a temperature of about 400-500 C., the improvement which comprises incorporating into the alloy composition, prior to extrusion, 0.05 to 0.45 of copper to reduce the required extrusion pressure.

12. A process as in claim 11, wherein the alloy composition additionally contains a minute quantity of at least one metal selected from the group consisting of titanium, magnesium, calcium, beryllium, barium, aluminum and zirconium, said quantity beng less than 0.3%, the remainder being cerium (misch metal).

References Cited by the Examiner UNITED STATES PATENTS 2,408,400 10/46 Kent -152 2,792,301 5/57 Bungardt 75135 X FOREIGN PATENTS 1,017,507 10/ 57 Germany.

A DAVID L. RECK, Primar Examiner. 10. A process as in claim 7, wherein the alloy addi- 30 y

Claims

1. A PYROPHORIC ALLOY COMPOSITION SUITABLE FOR EXTRUSION ESSENTIALLY CONSISTING OF ABOUT 4.5 TO 40% OF IRON AND 0.5 TO 0.45% OF COPPER, THE REMAINDER BEING CERIUM (MISCH METAL).